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: http://www.arcetri.astro.it/irlab/doc/library/javascript/clientreference/textarea.htm
Дата изменения: Thu Oct 7 13:13:35 1999 Дата индексирования: Sat Dec 22 14:35:37 2007 Кодировка: Поисковые слова: trifid nebula |
TEXTAREA
tag. For a given form, the JavaScript runtime engine creates appropriate Textarea
objects and puts these objects in the elements
array of the corresponding Form
object. You access a Textarea
object by indexing this array. You can index the array either by number or, if supplied, by using the value of the NAME
attribute.
To define a text area, use standard HTML syntax with the addition of JavaScript event handlers.
Textarea
object on a form looks as follows:
Textarea
object is a form element and must be defined within a FORM
tag.
Textarea
objects can be updated (redrawn) dynamically by setting the value
property (this.value
).
To begin a new line in a Textarea
object, you can use a newline character. Although this character varies from platform to platform (Unix is \n
, Windows is \r
, and Macintosh is \n
), JavaScript checks for all newline characters before setting a string-valued property and translates them as needed for the user's platform. You could also enter a newline character programmatically--one way is to test the navigator.appVersion
property to determine the current platform, then set the newline character accordingly. See navigator.appVersion
for an example.
Property |
Description
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Method |
Description
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watch
and unwatch
methods from Object
.
Textarea
object that is six rows long and 55 columns wide. The textarea field appears immediately below the word "Description:". When the form loads, the Textarea
object contains several lines of data, including one blank line.
<B>Description:</B>
<BR><TEXTAREA NAME="item_description" ROWS=6 COLS=55>
Our storage ottoman provides an attractive way to
store lots of CDs and videos--and it's versatile
enough to store other things as well.
It can hold up to 72 CDs under the lid and 20 videosExample 2. The following example creates a string variable containing newline characters for different platforms. When the user clicks the button, the
in the drawer below.
</TEXTAREA>
Textarea
object is populated with the value from the string variable. The result is three lines of text in the Textarea
object.
<SCRIPT>
myString="This is line one.\nThis is line two.\rThis is line three."
</SCRIPT>
<FORM NAME="form1">
<INPUT TYPE="button" Value="Populate the textarea"
onClick="document.form1.textarea1.value=myString">
<P>
<TEXTAREA NAME="textarea1" ROWS=6 COLS=55></TEXTAREA>
Form
, Password
, String
, Text
blur()
userText:
userText.blur()This example assumes that the textarea is defined as
<TEXTAREA NAME="userText">
Initial text for the text area.
</TEXTAREA>
Textarea.focus
, Textarea.select
Textarea
object.defaultValue
reflects the value specified between the TEXTAREA
start and end tags. Setting defaultValue
programmatically overrides the initial setting.
You can set the defaultValue
property at any time. The display of the related object does not update when you set the defaultValue
property, only when you set the value
property.
defaultValue
property of objects on the surfCity
form and displays the values in the msgWindow
window:
function defaultGetter() {
msgWindow=window.open("")
msgWindow.document.write("hidden.defaultValue is " +
document.surfCity.hiddenObj.defaultValue + "<BR>")
msgWindow.document.write("password.defaultValue is " +
document.surfCity.passwordObj.defaultValue + "<BR>")
msgWindow.document.write("text.defaultValue is " +
document.surfCity.textObj.defaultValue + "<BR>")
msgWindow.document.write("textarea.defaultValue is " +
document.surfCity.textareaObj.defaultValue + "<BR>")
msgWindow.document.close()
}
Textarea.value
focus()
focus
method to navigate to the textarea field and give it focus. You can then either programmatically enter a value in the field or let the user enter a value. If you use this method without the select
method, the cursor is positioned at the beginning of the field.
Textarea.blur
, Textarea.select
Textarea.select
.
form
property that is a reference to the element's parent form. This property is especially useful in event handlers, where you might need to refer to another element on the current form.
button2
, the function showElements
displays an alert dialog box containing the names of each element on the form myForm
.
function showElements(theForm) {
str = "Form Elements of form " + theForm.name + ": \n "
for (i = 0; i < theForm.length; i++)
str += theForm.elements[i].name + "\n"
alert(str)
}
</script>
<FORM NAME="myForm">The alert dialog box displays the following text:
Form name:<INPUT TYPE="textarea" NAME="text1" VALUE="Beluga">
<P>
<INPUT NAME="button1" TYPE="button" VALUE="Show Form Name"
onClick="this.form.text1.value=this.form.name">
<INPUT NAME="button2" TYPE="button" VALUE="Show Form Elements"
onClick="showElements(this.form)">
</FORM>
JavaScript Alert:Example 2. The following example uses an object reference, rather than the
Form Elements of form myForm:
text1
button1
button2
this
keyword, to refer to a form. The code returns a reference to myForm
, which is a form containing myTextareaObject
.
document.myForm.myTextareaObject.form
Form
handleEvent(event)
event | The name of an event for which the object has an event handler. |
name
property initially reflects the value of the NAME
attribute. Changing the name
property overrides this setting. The name
property is not displayed on-screen; it is used to refer to the objects programmatically.
If multiple objects on the same form have the same NAME
attribute, an array of the given name is created automatically. Each element in the array represents an individual Form
object. Elements are indexed in source order starting at 0. For example, if two Text
elements and a Textarea
element on the same form have their NAME
attribute set to "myField"
, an array with the elements myField[0]
, myField[1]
, and myField[2]
is created. You need to be aware of this situation in your code and know whether myField
refers to a single element or to an array of elements.
valueGetter
function uses a for
loop to iterate over the array of elements on the valueTest
form. The msgWindow
window displays the names of all the elements on the form:
newWindow=window.open("http://home.netscape.com")
function valueGetter() {
var msgWindow=window.open("")
for (var i = 0; i < newWindow.document.valueTest.elements.length; i++) {
msgWindow.document.write(newWindow.document.valueTest.elements[i].name + "<BR>")
}
}
select()
select
method to highlight the input area of a textarea field. You can use the select
method with the focus
method to highlight the field and position the cursor for a user response. This makes it easy for the user to replace all the text in the field.
onClick
event handler to move the focus to a textarea field and select that field for changing:
<FORM NAME="myForm">
<B>Last name: </B><INPUT TYPE="text" NAME="lastName" SIZE=20 VALUE="Pigman">
<BR><B>First name: </B><INPUT TYPE="text" NAME="firstName" SIZE=20 VALUE="Victoria">
<BR><B>Description:</B>
<BR><TEXTAREA NAME="desc" ROWS=3 COLS=40>An avid scuba diver.</TEXTAREA>
<BR><BR>
<INPUT TYPE="button" VALUE="Change description"
onClick="this.form.desc.select();this.form.desc.focus();">
</FORM>
Textarea.blur
, Textarea.focus
Textarea
objects, the value of the type
property is "textarea"
. This property specifies the form element's type. type
property for every element on a form.
for (var i = 0; i < document.form1.elements.length; i++) {
document.writeln("<BR>type is " + document.form1.elements[i].type)
}
VALUE
attribute. value
property at any time. The display of the Textarea
object updates immediately when you set the value
property.
value
property of a group of buttons and displays it in the msgWindow
window:
function valueGetter() {This example displays the following:
var msgWindow=window.open("")
msgWindow.document.write("submitButton.value is " +
document.valueTest.submitButton.value + "<BR>")
msgWindow.document.write("resetButton.value is " +
document.valueTest.resetButton.value + "<BR>")
msgWindow.document.write("blurb.value is " +
document.valueTest.blurb.value + "<BR>")
msgWindow.document.close()
}
submitButton.value is Query SubmitThe previous example assumes the buttons have been defined as follows:
resetButton.value is Reset
blurb.value is Tropical waters contain all sorts of cool fish,
such as the harlequin ghost pipefish, dragonet, and cuttlefish.
A cuttlefish looks much like a football wearing a tutu and a mop.
<INPUT TYPE="submit" NAME="submitButton">
<INPUT TYPE="reset" NAME="resetButton">
<TEXTAREA NAME="blurb" rows=3 cols=60>
Tropical waters contain all sorts of cool fish,
such as the harlequin ghost pipefish, dragonet, and cuttlefish.
A cuttlefish looks much like a football wearing a tutu and a mop.
</TEXTAREA>
Textarea.defaultValue
Last Updated: 05/28/99 12:00:43